The diagnosis of cancer is one of life's most distressing events, bringing in its wake the possibility of depression, which is an understandable, and normal, reaction to the disease, but could have grave consequences. Because of such an association, depression has been considered to have an impact not only on the progression, but also on the initiation, of cancer. Reactive oxygen species (ROSs), produced in the ordinary course of human life, have been shown to possess a potential role in the initiation, promotion, and progression of cancer. One of the base modifications due to oxidative stress is 8-hydroxydeoxyguanosine (8-OH-dG). It has been reported that this oxidative DNA damage indicates both mutagenesis and carcinogenesis, and has been considered to be useful in estimating cancer risk. Owing to these findings, the formation of 8-OH-dG seems to be a valuable biomarker to evaluate the possible stress-cancer linkage under natural and ordinary stress conditions.
A recent study, published in the November issue of Journal of Psychiatric Research, was conducted in Japan to ascertain the potential link between depression and cancer. The degree of depression was assessed by the scores of the center for epidemiologic studies depression scale (CES-D) and the profile of mood states (POMS). Researchers compared the cancer-related oxidative DNA damage, 8-hydroxydeoxyguanosine (8-OH-dG), in 30 patients with depression and 60 age- and gender-matched healthy controls, and examined the 8-OH-dG-related factors. The patients showed significantly higher 8-OH-dG levels than the controls. There was a significant positive correlation between the CES-D scores and the 8-OH-dG levels in depressive, particularly female, patients. Multiple regression analysis indicated that whether the subjects were patients or controls was a significant predictor of the 8-OH-dG levels in male and total subjects, as was the CES-D score or the Depression-Rejection score of the POMS in female subjects.
The study concludes on the note that although it may be overhasty to conclude that individuals with depression are generally at an increased risk of cancer, because it is uncertain whether subjects with high levels of 8-OH-dG really tend to develop cancer, however, this provides suggestion that clinical depression is a risk factor for cancer initiation due to oxidative DNA damage.